In general, flow meters are devices that measure the amount of liquid, gas or vapor that passes, for example, through a pipeline. Flow can be measured in a variety of ways. Both gas and liquid for example can be measured in volumetric or mass flow rates. The volumetric flow rate, for example, is the volume of fluid which passes through a given surface per unit time, e.g., cubic meters per second.
A flow meter is generally an arrangement, which consists of several components. Known electronic count flow meters include one or more sensors, an optical or electronic sensor interface, a microcontroller and in most cases some kind of display and communication. A flow meter might also be able to control a valve, for example, in order to control the flow. The microcontroller in known electronic count flow meters typically performs the sampling of the sensors, receives the measurement signals and processes them. Through an interface, the microcontroller can then access the display to make the results of the measurements visible to a user. In case the microcontroller detects, that the flow is too fast or too slow, it could control and adjust the flow, by opening or closing a valve, for example.
In order to keep track of the flow to be measured, sampling of the sensors has to be performed at regular intervals. For this, the microcontroller needs to be in an active state. During intervals, in which no sampling is performed, the microcontroller can change into a sleep mode to reduce power consumption.
Flow meters are often battery powered. Therefore a low power consumption is desirable, to allow operation of the flow meter for typically at least up to 20 years, without the need of a battery change.